Certain abbreviations that are found herein are defined as follows:    3GPP third generation partnership project    UE user equipment    NW network    DRX discontinuous reception    DTX discontinuous transmission    PS packet scheduling    NC network controlled    LTE long term evolution    RRC radio resource control    RNC radio network controller    DCH dedicated channel
One potential problem related to current discontinuous reception/transmission and packet scheduling concepts being developed is that these concepts are based on a very flexible discontinuous reception/transmission and packet scheduling scheme to allow the user equipment to save power when neither data reception (RX) nor transmission (TX) is scheduled for the user equipment. The user equipment typically enters a discontinuous mode (e.g., as opposed to a continuous mode) of reception or transmission. Discontinuous data reception typically means that neighbor cell measurements performed by the user equipment are also impacted, as user equipment-based measurements (e.g., especially intra-frequency measurements) normally are scheduled in the user equipment to be performed at the same time that reception or transmission is to occur. This scheduling is due to power saving. A current packet scheduling scheme has a side effect that the user equipment-based measurement can occur in an unpredictable manner.
As it is expected that in the LTE (also called 3.9G) concept, no RRC state change is required for the user equipment to begin using discontinuous reception/transmission, the change of certain parameter (such as Time-to-Trigger or Treselection parameters, described below) values generally should not be simply tied to state changes. Instead, another approach is required. The foregoing problems have not yet been addressed in 3.9G.
However, previously in 2G and 3G systems the same or a similar problem has been addressed. In 3G, where Time-to-Trigger and Treselection parameters and concepts were introduced, there is no RRC state, where the user equipment is occasionally required to receive data without interruption due to discontinuous reception (e.g., DRX) and while during some other moments it is allowed to use discontinuous reception for power saving purposes. This means that power saving benefits can be achieved without state transitions.
In the 2G systems, the measurement reporting by the user equipment in a dedicated mode is periodic and is based on time. In this state, no hysteresis or Time-to-Trigger approach is used. For example, a measurement report is sent every 0.48 second (excluding a Fast Power Control operation, which is also timer based). In a case where the user equipment is GPRS attached, the user equipment may be ordered to perform network controlled measurements. In this case, the measurement reporting to the network is controlled by a NC_REPORTING_PERIOD timer. This timer may vary depending on whether the user equipment is in transfer or idle mode. The timer value given by the network is used by the user equipment until a new value is received, with the exception that if the time for reporting in idle is shorter than the discontinuous reception time, the user equipment uses the discontinuous reception time as the reporting time interval.
3G measurement reporting may be based on an event trigger, which also includes a Time-to-Trigger parameter for some short time-domain “hysteresis”. Without the Time-to-Trigger parameter, a user equipment would immediately report a measurement (e.g., of power level of a signal being received) when the measurement meets certain criteria, which typically involves the measurement (or measurements) being beneath some threshold for some period of time. The Time-to-Trigger parameter provides a time period during which an evaluation may be made as to whether the measurement meets the criteria. This Time-to-Trigger time period therefore reduces reporting of events caused when, e.g., a signal level temporarily dips below a threshold. The Time-to-Trigger parameter is signaled to the user equipment by the network. The network signals only one Time-to-Trigger parameter at a time, and the user equipment uses that parameter until a new Time-to-Trigger parameter value is signaled to the user equipment.
In addition to the Time-to-Trigger parameter for event-triggered reporting in the CELL_DCH, 3G has the Treselection parameter for cell reselection purposes in the Idle mode and the CELL_PCH, URA_PCH and CELL_FACH states. The Treselection parameter is broadcast to the user equipment in the System Information. In the first releases of 3G, one Treselection parameter was defined for the Idle mode and another for RRC-connected modes, where cell reselections are performed (i.e., CELL_PCH, URA_PCH and CELL_FACH). In the later releases, CELL/URA_PCH and CELL_FACH Treselection parameters were separated from each other, such that during CELL_PCH/URA_PCH states the user equipment may utilize discontinuous reception, and in the case of discontinuous reception the user equipment does not perform continuous measurements. The discontinuous reception cycle length is also likely to affect the measurement activity, as allowed by 3GPP TS 25.133. In the CELL_FACH state, however, the user equipment cannot utilize discontinuous reception and the continuous neighbor measurements are also required.
While all of these different parameters and corresponding time periods used for evaluation are useful, it is beneficial to adjust the parameters and corresponding time periods in ways not previously performed.